A new Early Jurassic (ca. 183 Ma) fossil Lagerstätte from Ya Ha Tinda, Alberta, Canada
Rowan C. Martindale1,2*, Theodore R. Them II3,4, Benjamin C. Gill3, Selva M. Marroquín1,3, and Andrew H. Knoll2 1Department of Geological Sciences, The University of Texas at Austin, 1 University Station C1100, Austin, Texas 78712, USA 2Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, Massachusetts 02138, USA 3Department of Geosciences, Virginia Polytechnic Institute and State University, 4044 Derring Hall (0420), Blacksburg, Virginia 24061, USA 4Department of Earth, Ocean and Atmospheric Science & National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
ABSTRACT Figure 1. Global paleoge- Lagerstätten—deposits of exceptionally preserved fossils—offer ography during Toarcian vital insights into evolutionary history. To date, only three Konservat- and location of Ya Ha Tinda Hispanic (Alberta, Canada; yellow Lagerstätten are known from Early Jurassic marine rocks (Osteno, Corridor Tethys star), Strawberry Bank (UK; Posidonia Shale, and Strawberry Bank), all located in Europe. We gray star), and Posidonia report a new assemblage of exceptionally preserved fossils from Panthalassa Shale (Germany; black star) Alberta, Canada, the first marine Konservat-Lagerstätte described Lagerstätten. Green areas are Pangea landmasses, light-blue areas from the Jurassic of North America. The Ya Ha Tinda assemblage are shallow seas, and dark includes articulated vertebrates (fish, ichthyosaurs), crinoids, crus- blue represents open oceans. taceans, brachiopods, abundant mollusks (coleoids with soft tissues, ammonites, gastropods, bivalves), wood, and microfossils. Paired bio- METHODS and chemostratigraphies show that Lagerstätte deposition occurred Exposures of the Fernie Formation at the Ya Ha Tinda Ranch (south- during the late Pliensbachian through early Toarcian, capturing the west Alberta) were measured and described in centimeter-scale detail; carbon isotope excursion associated with the Toarcian Oceanic Anoxic exact localities cannot be disclosed. Intervals with exceptional preserva- Event. Therefore, the Panthalassan Ya Ha Tinda biota is coeval with tion (e.g., Fig. 2) were quarried and specimens prepared for study (repos- Toarcian Lagerstätten from the Tethys Ocean (Posidonia Shale and ited at the Royal Tyrrell Museum of Palaeontology, Canada); see the Strawberry Bank). Comparisons among these deposits permit new GSA Data Repository1 for extraction, preparation, and analytical techniques. insights into the diversity, ecology, and biogeography of Jurassic marine communities during a time of pronounced biological and RESULTS environmental change (e.g., expanded subsurface anoxia, warming, and extinctions). They also highlight the possibility that Mesozoic Ya Ha Tinda Biota Oceanic Anoxic Events are temporal foci of exceptional preservation. At Ya Ha Tinda, exceptionally preserved fossils can be found in both the Red Deer and Poker Chip Shale members of the Fernie Formation (Fig. INTRODUCTION 2). Platy calcareous shales interbedded with fine siltstones and black lime- During the Early Jurassic there were several major environmental and stones compose the late Pliensbachian–early Toarcian Red Deer Member, ecological perturbations that influenced Mesozoic evolution, notably the whereas the Toarcian Poker Chip Shale is composed of poorly cemented, Toarcian Oceanic Anoxic Event (T-OAE). The T-OAE is associated with black calcareous shales and mudstones interbedded locally with bitu- benthic and pelagic extinctions including ammonites, fish, foraminifers, minous limestones (Fig. 2; Them et al., 2017). Ages of these units are radiolarians, corals, bivalves, and brachiopods (e.g., Little and Benton, constrained by ammonite and coccolith biostratigraphy, carbon isotope 1995; Lathuilière and Marchal, 2009; Caruthers et al., 2014; Caswell and chemostratigraphy, and U-Pb zircon dates from intercalated ash beds in Coe, 2014; Danise et al., 2015). Compelling as this record may be, it is outcrops at Ya Ha Tinda Ranch (Hall et al., 2004; Them et al., 2017). Well- biased; unbiomineralized organisms are rarely preserved, yet represent preserved specimens have previously been collected, mostly from float the majority of marine biodiversity (e.g., Schopf, 1978; Morris, 1986). (Hall, 1985, 1991; Feldmann and Copeland, 1988), but the full scope of While unusual environmental circumstances allow for preservation of preservation (i.e., soft tissue preservation at multiple horizons) and fossil soft tissues and provide a more complete perspective on evolutionary abundance has only recently become apparent. The preservation of cuticle history in Konservat-Lagerstätten (Seilacher, 1970; Briggs, 2003), only (arthropod carapaces) and soft tissue (coleoid ink sacs and mantle muscle two occur within the T-OAE: the Posidonia Shale (primarily) in Germany tissue) (Fig. 3) marks this deposit as a Konservat-Lagerstätte. (e.g., Seilacher, 1990) and the British Strawberry Bank Lagerstätte (Wil- Coleoid cephalopods, specifically Vampyropoda (eight-armed, gladius- liams et al., 2015). bearing coleoids), exhibit the most exceptional preservation. Vampyropod Here we describe a new Early Jurassic (Pliensbachian–Toarcian) specimens (Figs. 3D–3E) include isolated gladii (chitinous internal shell), Lagerstätte from Alberta, Canada: the Ya Ha Tinda assemblage (Fig. 1). gladii and ink sacs, and gladii with mantle muscle and ink sacs. Chitinous This deposit is significant as both the first marine Konservat-Lagerstätte described from the Jurassic of North America and the first described 1 GSA Data Repository item 2017066, sample excavation, preparation, and ana- Pliensbachian–Toarcian Lagerstätte outside of Europe. lytical methods, lithological description, and additional fossil images, is available online at www.geosociety.org/datarepository /2017 or on request from [email protected] *E-mail: [email protected] geosociety.org.
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. ) Legend 13 ) Limestone δ Corg (% VPDB) -31--30 29 -28 -27-26 Poorly cemented calcareous mudstone LithostratStage Zone Zone(Eu (NA)Strat. height Ya Ha Tinda Fossils 22 (m Calcareous mudstone Calcareous siltstone/concretion a 20 Unfossiliferous calcareous siltstone Interbedded limestone with thin shale lanulat bifrons 18 Interbedded shale/limestone Shell Bed Ash Bed (Bentonite) 16
arcian Barite/Gypsum Needles
To Vampyropoda body fossil 14 ep
Poker Chip Shale Member Lobster body fossil
erpentinum T-OAE Shrimp body fossil or appendage anens 12 CIE Crustacean appendage
ns Articulated fish fossil te 10 Articulated crinoid/Crinoid Ossicle Bone (vertebrae) 8 Bivalve spinatum arlottens ek Brachiopod 6 Ammonite/Aptychus Atractites sp. (belemnite-like coleoid) 4 Wood Red Deer Member Coprolite Pliensbachia n kuna ec Diplocraterion trace fossil
margaritatus 2 Thalassinoides trace fossil Arenicolites trace fossil 0 Rhizocorallium trace fossil
silt -31--30 29 -28 -27-26
lim e mu d Rusophycus trace fossil shale
Figure 2. Stratigraphic column of East Tributary of Bighorn Creek section (Fernie Formation, Ya Ha Tinda, Alberta, Canada) with fossil occur- rences (Royal Tyrrell Museum of Palaeontology locality L2428). Chemostratigraphic and biostratigraphic data are modified from Them et al. (2017). Lithostrat.—lithostratigraphy; Strat. height—stratigraphic height in section; Zone (Eu)—northwestern Europe ammonite zonation; Zone (NA)—western North America ammonite zonation; ten.—tenuicostatum; org—organic; VPDB—Vienna Peedee belemnite; T-OAE CIE— Toarcian Oceanic Anoxic Event carbon isotope excursion.
tissues typically preserve relatively well (Kear et al., 1995); ink sac pres- aptychi. Additional fossils include a dinosaur bone, brachiopods, gastro- ervation is less easily accounted for, but may relate to the abundance of pods, bivalves, wood, and coccolithophores (Hall, 1991; Hall et al., 1998). decay-resistant melanin in this organ (Glass et al., 2012) and clay min- Ya Ha Tinda bivalves are abundant and taxonomically similar to those eral authigenesis. Recent excavations have uncovered fifteen specimens of from Europe (e.g., Röhl et al., 2001). Compressions of transported logs vampyropods (Figs. 2 and 3; mostly loligosepiids and prototeuthids), making have been found, but no crinoids or bivalves have been attached to them. this the largest known deposit of Jurassic vampyropods outside of Europe. Crustacean preservation at Ya Ha Tinda is excellent. Specimens include Paleoenvironment and Preservation compressions of appendages and fully or partially articulated carcasses Soft tissue preservation has been identified at three different Ya Ha Tinda (Figs. 3F–3H). Full lobster carapaces have only been found below the Ranch outcrops, but the best in situ material occurs in beds exposed along T-OAE carbon isotope excursion (CIE), whereas appendages occur a tributary of Bighorn Creek (herein called East Tributary). The Lagerstätte throughout the studied interval. Ya Ha Tinda crustaceans include a shrimp interval (Fig. 2) occurs from the North American kunae ammonite zone (Fig. 3F) as well as lobsters such as Uncina ollerenshawi (Feldmann and of the late Pliensbachian (Red Deer Member) to the planulata zone of the Copeland, 1988; Schweigert et al., 2003), the first complete specimen of middle Toarcian (Poker Chip Shale Member) (Them et al., 2017). This Uncina pacifica (appendages from this site described by Schweigert et interval corresponds to the margaritatus through bifrons European zones al. ; Fig. 3G), a new Uncina species, and an undetermined eryonid (Pálfy and Smith, 2000) and contains the T-OAE CIE (Them et al., 2017). lobster with thin, scissor-like claws (Fig. 3H). Previous studies on the Red Deer and Poker Chip Shale members have Other fossils include articulated vertebrates, the most abundant of suggested that deposition occurred on a gently sloping shelf to basin and which are leptolepiform and saurichthyiform fish (Fig. 3B). Ichthyosaurs that the water column was recurrently to persistently dysoxic to anoxic and fish also occur as lone vertebrae, vertebral columns (Fig. 3A), and (Stronach, 1984; Hall, 1985, 1991; Hall and Neuman, 1989; Ross and articulated skeletons with skulls (Hall et al., 1998). Important invertebrate Bustin, 2006), which accounts for the high organic carbon content (0.3–7.6 finds include articulated crinoid stems up to 1.75 m long (Seirocrinus wt%; total organic carbon [carbonate-free] is 2.0–35.5 wt% [Them et al., sp.) and a Seirocrinus subangularis calyx (Hall, 1991) (Fig. 3C), as well 2017]) and lack of skeletal disarticulation (scavenging) throughout the as numerous Atractites sp. (an aulacocerid coleoid), several preserved East Tributary section. Still, in Pliensbachian strata, the presence of mac- with soft tissues. Ammonites are abundant and occasionally occur with roscopic bioturbation, benthic fauna, and large bivalves and brachiopods
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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/45/3/255/3550683/255.pdf by guest on 02 October 2021 Figure 3. Exceptionally preserved fossils of Ya Ha Tinda Lagerstätte (Alberta, Canada; specimen numbers are provided in Data Repository [see footnote 1]). RDM—Red Deer Member; PCS—Poker Chip Shale Member. A: Articulated ichthyosaur vertebrae and ribs (RDM, late Pliens- bachian). B: Skull of small teleost fish (PCS, within Toarcian Oceanic Anoxic Event [T-OAE] carbon isotope excursion [CIE]); note preservation of gills (arrow). C: Seirocrinus subangularis (crinoid) calyx collected by Russell Hall (RDM, late Pliensbachian). D: Vampyropod gladius with mantle muscle (white arrow) and ink sac (black arrow) (RDM, early Toarcian). E: Loligosepiid vampyropod gladius with ink sac (arrow) (RDM, early Toarcian). F: Shrimp body fossil (PCS, within T-OAE CIE). G: Complete body fossil of Uncina pacifica lobster, proximodistally flattened (RDM, late Pliensbachian). H: Complete body fossil of eryonid lobster, dorsoventrally flattened, ventral view (RDM, late Pliensbachian).
suggests persistent, multi-annual episodes of oxygenation. At the onset of 2002; Williams et al., 2015; Them et al., 2017). Significantly more mate- the T-OAE CIE, benthic fauna experienced a major turnover and diminu- rial has been discovered at European Lagerstätten, but Ya Ha Tinda is tion in size, bioturbation ceased, and benthic colonization events became exceptionally productive and may in time rival these deposits. Additionally, ephemeral, while nektonic fauna persisted. These data collectively suggest at Ya Ha Tinda, soft tissue preservation occurs through a more expanded a role for dysoxic or anoxic bottom waters during the T-OAE in control- interval, which includes the late Pliensbachian. Importantly, these con- ling soft tissue preservation, faunal distribution, and diversity. temporaneous Lagerstätten collectively allow for direct comparisons Exceptional preservation occurs in multiple horizons, but the best of Early Jurassic biodiversity, environments, ecology, and fossilization soft tissue preservation occurs just below the T-OAE CIE (Fig. 2). Fos- between northeastern Panthalassa and the Tethys Ocean. silized tissues contain high levels of carbon, calcium, phosphorous, and Despite the paleogeographic separation of the Toarcian Lagerstätten sulfur when compared with surrounding matrix, suggesting preservation (Fig. 1), their faunas are similar. Each contains ichthyosaurs, ray-finned as carbonaceous compressions and mineral replacements (apatite and fishes, gladius-bearing coleoids, crustaceans, ammonites, bivalves, and occasionally clay minerals). Rarely, bivalve shells exhibit pyritization, crinoids. In many cases, families or genera are the same or sister taxa, but but typically remain calcified. All soft tissues (ink sacs being the excep- species vary by ocean basin. Lobsters exemplify this: Ya Ha Tinda uncinid tion) occur as two-dimensional compressions (Fig. 3); only calcified hard lobsters, U. pacifica, U. ollerenshawi, and Uncina sp. 1, are unique to parts (e.g., proostracum, crinoid ossicles, bones) are preserved in three Panthalassa, whereas Uncina posidoniae and Uncina alpina only occur in dimensions. These observations imply that mineralization occurred after Europe (Schweigert et al., 2003). This strong faunal link between deposits tissue collapse (Briggs and Kear, 1993). Carbonization and phosphatiza- suggests similar ecosystems and connections between basins (e.g., the tion appear to have been the primary taphonomic pathways, and unlike Hispanic corridor; Fig. 1). Furthermore, the T-OAE biotic turnover is in the Posidonia Shale, pyritization is rare. present at Ya Ha Tinda, confirming the global nature of this crisis (e.g., Little and Benton, 1995; Caruthers et al., 2014). DISCUSSION AND CONCLUSIONS In terms of depositional environment and taphonomic processes, Ya The Ya Ha Tinda Lagerstätte is contemporaneous with the Posidonia Ha Tinda and the Posidonia Shale appear to be the most similar. The Shale and Strawberry Bank Lagerstätten; all three span the tenuicostatum host lithology of both is bituminous shales intercalated with limestones, and bifrons zones of the early Toarcian (Jenkyns, 1988; Etter and Tang, and episodic bottom-water anoxia has been invoked for both to explain
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Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/45/3/255/3550683/255.pdf by guest on 02 October 2021 exceptional preservation (Seilacher, 1982; Röhl et al., 2001; this study, Glass, K., et al., 2012, Direct chemical evidence for eumelanin pigment from the Ju- and references therein). In both Lagerstätten, specimens are flattened and rassic period: Proceedings of the National Academy of Sciences of the United States of America, v. 109, p. 10,218–10,223, doi:10.1073/pnas.1118448109. tissues preserved as carbonaceous compressions or through authigenic Hall, R.L., 1985, Paraplesioteuthis hastata (Münster), the first teuthid squid re- mineralization (apatite and clay minerals); pyritization and preservation in corded from the Jurassic of North America: Journal of Paleontology, v. 59, nodules are more common in the Posidonia Shale. In contrast, Strawberry p. 870–874. Bank is interpreted to represent a nearshore, shallow marine environment Hall, R.L., 1991, Seirocrinus subangularis (Miller, 1821), a Pliensbachian (Lower Jurassic) crinoid from the Fernie Formation, Alberta, Canada: Journal of Pa- due to the abundance of insect fossils; additionally, fossils are predomi- leontology, v. 65, p. 300–307, doi:10 .1017/S0022336000020539. nantly preserved as three-dimensional specimens in calcareous nodules Hall, R.L., and Neuman, A.G., 1989, Teudopsis cadominensis, a new teuthid squid or muddy limestones (Williams et al., 2015). from the Toarcian (Lower Jurassic) of Alberta: Journal of Paleontology, v. 63, The three Toarcian Lagerstätten provide a unique opportunity to study p. 324–327, doi:10.1017/S0022336000019478. contemporary taphonomic pathways in similar, but geographically separate, Hall, R.L., Poulton, T.P., and Monger, J.W.H., 1998, Field trip Al: Calgary - Van- couver, in Smith, P. L., ed., Field Guide for the Fifth International Sympo- ecosystems. Furthermore, the abundance of coeval Lagerstätten implies sium on the Jurassic System: Vancouver, Canada, Jurassic Subcommission that Mesozoic Oceanic Anoxic Events may be poorly appreciated sources of the Stratigraphic Commission of the International Union of Geological of exceptional fossil deposits. Anoxia has long been known as a necessary Sciences, p. 29–61. environmental control on many preservational pathways, but it alone is Hall, R.L., McNicoll, V., Gröcke, D., Craig, J., and Johnston, K., 2004, Integrated stratigraphy of the lower and middle Fernie Formation in Alberta and British insufficient to induce soft tissue preservation (summarized in Briggs, 2003). Columbia, western Canada: Rivista Italiana di Paleontologia e Stratigrafia, The discovery of the Ya Ha Tinda Lagerstätte means that we can, for v. 110, p. 61–68. the first time, compare exceptionally preserved Early Jurassic marine Jenkyns, H.C., 1988, The early Toarcian (Jurassic) anoxic event: Stratigraphic, faunas from the two major ocean basins (Fig. 1). This rare occurrence sedimentary and geochemical evidence: American Journal of Science, v. 288, p. 101–151, doi:10.2475/ajs.288.2.101. will allow for a much more nuanced understanding of global biogeogra- Kear, A.J., Briggs, D.E.G., and Donovan, D.T., 1995, Decay and fossilization of non- phy, taphonomic controls on preservation, and the relationships of Early mineralized tissues in coleoid cephalopods: Palaeontology, v. 38, p. 105–131. Jurassic communities between different ocean basins. Importantly, Ya Lathuilière, B., and Marchal, D., 2009, Extinction, survival and recovery of corals Ha Tinda fossils add to the documentation of a persistent nektonic and from the Triassic to Middle Jurassic time: Terra Nova, v. 21, p. 57–66, doi: pelagic marine community during a time of increased biotic turnover, 10.1111/j.1365-3121.2008.00856.x. Little, C.T.S., and Benton, M.J., 1995, Early Jurassic mass extinction: A global constraining interpretations of evolution during an interval of global envi- long-term event: Geology, v. 23, p. 495–498, doi:10 .1130 /0091 -7613 (1995)023 ronmental perturbation. <0495:EJMEAG>2.3.CO;2. Morris, S.C., 1986, The community structure of the Middle Cambrian Phyllopod ACKNOWLEDGMENTS Bed (Burgess Shale): Palaeontology, v. 29, p. 423–467. This manuscript is dedicated to the late Russell Hall who discovered the first excep- Pálfy, J., and Smith, P.L., 2000, Synchrony between Early Jurassic extinction, tional fossils at Ya Ha Tinda. We thank R. and J. Smith, the Ya Ha Tinda Ranch oceanic anoxic event, and the Karoo-Ferrar flood basalt volcanism: Geology, caretakers, as well as S. Hairsine, D. Petersen, B. Perry, G. Sundbo, and D. Gummer v. 28, p. 747–750, doi:10 .1130 /0091 -7613 (2000)28 <747: SBEJEO>2 .0 .CO;2. at Parks Canada for research permits and logistical support (permit YHTR-2014- Röhl, H.-J., Schmid-Röhl, A., Oschmann, W., Frimmel, A., and Schwark, L., 2001, 16156). D. Brinkman, B. Strilisky, G. Housego, R. Russell, D. Spivak, J. McCabe, The Posidonia Shale (Lower Toarcian) of SW-Germany: An oxygen-depleted and D. Tanke at the Royal Tyrrell Museum of Palaeontology are sincerely thanked ecosystem controlled by sea level and palaeoclimate: Palaeogeography, Pa- for their aid with permits, logistical support, and fossil curation (permits 13-058, laeoclimatology, Palaeoecology, v. 165, p. 27–52, doi:10.1016/S0031-0182 14-009, and 15-019). We thank A. Gerhardt, J. Lively, and E. Tulsky for assistance (00)00152-8. in the field, D. Zhao for SEM analysis, as well as J. Schmitt, D. Briggs, R. Gaines, Ross, D.J.K., and Bustin, R.M., 2006, Sediment geochemistry of the Lower Juras- M. Benton, D. Rudkin, C. Brett, and two anonymous reviewers whose advice sic Gordondale Member, northeastern British Columbia: Bulletin of Canadian greatly improved this manuscript. RCM and AHK thank the NASA Astrobiological Petroleum Geology, v. 54, p. 337–365, doi:10.2113/gscpgbull.54.4.337. Institute; RCM also thanks The University of Texas at Austin for a 2014 Jackson Schopf, T.J.M., 1978, Fossilization potential of an intertidal fauna: Friday Harbor, School of Geosciences seed grant. A grant to BCG from the National Science Washington: Paleobiology, v. 4, p. 261–270, doi:10.1017 /S0094837300005996. Foundation (grant EAR-1324752) also funded this work. 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